Time delay device



May 8, 1962 Filed Jan. 26, 1959 F. LICHTGARN TIME DELAY DEVICE 2Sheets-Sheet 1 FIG.b

y 1952 F. LICHTGARN 3,034,026

TIME ,DELAY DEVICE Filed Jan. 26, 1959 2 Sheets-Sheet 2 FIG.8

IN V EN TOR.

BY QMQL Lgu m 3,fl3 ,l}26 TE'MIE DELAY DEVEQE Fred Lichtgarn, 34Franklin St, Northlalre, ill. Filed .lan. 25, 1 59, Ser. No. 789,101 4Claims. (QB. 317-4175) This invention relates to electro-mechanical timedelay devices. At present, these devices are operated by air or liquidleakage, by clock type movements, or by thermal means.

This invention adds a new method to the above in that the alternationsin an AC. current are utilized in a novel manner. Alternating currentrapidly changes from maximum to almost zero and back to maximum. In 60cycle current this happens 120 times a second and produces thecharacteristic humming sound. If A.C. current is used to energize thecoil of a solenoid, for instance, the plunger will be magneticallypulled in and released 120 times a second. During the very briefintervals when the current is zero the plunger is free of magneticattraction. Therefore, if an external rotative force is applied to theplunger, it will slowly rotate in its sleeve during the brief intervalthat the magnetic flux is zero. However, the plunger cannot rotate veryfar before the current increases to a maximum and so the plunger isforced to stop its rotation. Thus we have a condition of stop and gothat can be used for time delay purposes. 1 term this action A.C. slip."It is a sort of controlled and controllable mechanical slippage orcreep.

The A0. slip effect depends on the strength of the external rotativeforce, on the magnetic efficiency of the electro-magnetic design, on theamount of electrical shading present, on the amount of friction, on theamount of lubrication and other similar contributing factors.

By a combination of the variables above and through the use of gearing,time delays from seconds to minutes and longer may be obtained. Also, bycontrolling the magnetic flux intensity by an external variac aconveniently adjustable time delay control is possible from a remotepoint.

It is to be understood that the AC. slip effect is not confined torotetive designs but may be adapted to other mechanical configurations.

Since it now takes time for a plunger to rotate or a shaft to slide or adisc to rotate, we can couple the moveable parts to any other suitablemechanism and thereby impart a time delay to the control of thatmechanism, switch or valve.

The main objective is to provide another means of time delay whichoperates by a new principle.

Another objective is to make a time delay device that has relatively fewparts.

Another objective is simplicity: only one moving part.

Another objective is a low cost device.

Another objective is to make a time delay device that can be variedelectrically-and from a remote point.

Another objective is to make a device that is rugged.

Another objective is to make a device that is relatively vibrationproof.

ther objects and uses will be apparent from the following descriptionand drawings.

Referring to the drawings,

PEG. 1 is shown to simply and clearly illustrate the working principleof the invention.

FlG. 2 is a cross-section view of one variation utilizing flatfrictional surfaces.

MG. 3 is a cross-section view of another solenoid variation utilizing atapered cone for the frictional surfaces.

aaaaazs iatented May 8, 1932 FIG. 4 is a cross-section view of anothermechanical and electrical variation utilizing fiat frictional surfacesand a conventional electro-magnet. It is not a solenoid.

FIG. 5 is a cross-section view of another variation which utilizes anelectro-rnagnet Whose polepiece is in contact with a rotatable disc madeof a material which can be attracted by an electro-mag'net.

FIG. 6 is a diagrammatic view of another variation in which magnetizedbearings grip a shaft moving along the path of the arrow. A forceagainst the shaft causes it to creep slowly through the magneticbearings.

FIGS. 7 and 8 are top and front views of a complete working apparatuswhich can produce a time delay in the controlled electric circuit.

Although the above is shown to clearly illustrate a few possiblevariations, it is understood that many other Variations of utilizin thisnew principle are entirely possible to anyone skilled in these arts.

Referring again to the drawings, in FIG. 1 We have a conventionalsolenoid in cross section. If the variac 6 is adjusted to apply fullvoltage to coil 1 the plunger 2 will be tightly held in its normalposition in frictional contact with the polepiece 7 and be almostimmovable. Now the rubber band 3 is fastened to the end of the plunger 2and twisted manually until a positive degree of tension is exertedrotatively when the rubber band is looped over pin 4. The tension willprobably not be strong enough to cause plunger 2 to rotate, but if thevariac 6 is slowly adjusted to lower the applied voltage on the coil land thus the frictional pull against the polepiece '7, a point will bereached Where a slight humming sound will be heard. it the plunger 2 isnow carefully watched one can see a very slowly creepage in the plungeras it rotates by AC. slip effect. Each time the current goes to zero theplunger moves (rotates) very slightly, but before it can move anydistance the current comes on to keep it in place. Thus for each cycleof the current the plunger is impelled by the rubber band to creep alittle. This is the time delay. Adjusting the variac will provide fasterand slower rotation. When the rubher band unwinds the rotation will stopof course. Instead of the rubber band we may have any external source ofenergy such as gravity, an electric clock motor, a spring or evencompressed air. One design could be made where a clock type electricmotor will be operated in a semi-stalled condition to supply theenergizing force necessary to cause the AC. slip effect to occur.

In FIG. 2 we have a solenoid construction also, where 3 is theelectro-magnet coil, the plunger 11 has an integral face disc on itwhich is in frictional contact with stationary frictional face surface10. The plunger does not quite touch the polepiece 9 because we want thefull force of the pull to take place at the fiictional faces of plunger11 and surface it). With more friction a slower rotative efiect cangenerally be obtained. In the conven tional solenoid only a limitedamount of friction can be obtained. This design is shown Where anincreased area of frictional contact is made available. Shaft 12connects to the associated equipment to be controlled.

in FIG. 3 we have also a solenoid with a specialized cone shaped plunger16 to provide increased frictional surface area when in contact withfixed frictional surface face 15. The plunger does not quite touchpolepiece 14. The coil is 13 and the shaft 17 connects to associatedapparatus. it is to be understood that the plunger ll: could be made ofa permanent magnet or of a ceramic type magnet so that a sort ofamplified A.C. slip can occur due to the mutual attraction and repellingeffect of a permanent magnet when used in an AC. circuit.

In PEG. 4 we have an electro-magnet utilizing the full magnetic fluxbecause it is a closed path. Coil 18 magattraction to take place at thefrictional faces 19A and thus strongly attracting rotative disc 21 whichis connected to shaft 22. Bearing 29 holds shaft so that disc 21.isparallel with faces HA.

In FIG. we have a regular electro-magnet with coil 23 and with extendedpolepiece 24 in contact with disc 25 which is made of any materialattracted by magnetism. Shaft as is attached to disc 25 and rotates withit. If there is no current in coil 23 the disc will be free to rotate.But if current is applied to coil 23 the disc will be strongly attractedto the polepiece and the rotation will be retarded to a very slowrotation due to the AC- slip eifcct. The speed of rotation can becontrolled by the strength of the current in coil 23. This then gives acontrollable time delay to any equipment which may be attached to shaft26.

In FIG. 6 We have a coil 27 magnetizing core fill and in turn hollowpolepieces 28 and 28A through which shaft 29 can travel. As shaft 29 isimpelled by an external force along the arrow an A.C. slip effect occursto re tard the free motion to a controlled slow motion which is timedelay.

In FIGS. 7 and 8 we have a complete simple operating unit forillustrative purposes mounted on a base ill.

Electro-magnet. coil 36 surrounds solenoid plunger 37 and both are heldin place by brackets Rod 38 is attached to plunger 37, and has a weight39 held in place by set-screw 39A. Microswitch 34 controls theassociated external circuit and also the coil magnetism of theelectro-magnet 36. In use rod 33 is manually lifted as shown. Thisimmediately causes switch 34 to close its contacts, coil 36 is energizedand the external circuit is on. As the rod 33 and weight 3% slowly falldue to gravity and the A.C. slip etfect a time delay occurs so that theexternal circuit remains on for a predetermined time interval. Thetiming period may be adjusted by moving the weight 39A along the rod. 41is a leaf spring which contacts the operating button in the microswitch.Bracket 33 holds switch 3d in place. 32 is the incoming connection blockand 31 is the outgoing connection block for the electric current. As therod slowly falls to reach the position shown in the dotted lines theswitch is opened and the coil and external circuit is also opened.

Having thus illustrated the manner in which the principles of thisinvention may be applied, What is claimed is:

1. A variable time delay device comprising an electromagnetic-solenoidlike structure with a hollow core having a fixed magnetic stop at oneend, with a movable armature in said hollow core, with separatelypowered rotative means acting upon said armature and with otherseparately powered counter-force means also acting upon said armature toexert a force counter to the magnetic attractive forces generated bysaid electromagnet, with the said rotative means co-operative with thesaid counterforce means to cause said armature to momentarily free 4;,itself of both frictional restraint and residual magnetic restraint whensaid electromagnet is at its low point in the changing cycle ofperiodically varying electrical input so that said armature could thenbegin to rotate, and with the said rotative and counterforccs nullifiedwhen the said electromagnet is energized by an increasing power input inthe said changing cycle, and With the rotative speed of said armaturebeing dependent upon and controllable by the amount of electrical energybeing fed into said electromagnet.

2. A variable speed timed delay clutching device comprising arielectromagnet having a hollow center, with an armature slidably androtatively positioned in said hollow center, with said armature having africtional face can tacting another frictional face attached to saidelectromagnet, with attachment means to couple an external rotativepower source to said armature, with means to connect a periodicallycycled varying power input into said electromagnet, with no armaturerotation occurring when said elec omagnet is fully energized, and with adegree of rotation occurring when said electromagnet has a reducedmagnetic strength due to said varying power input, and with the speed ofrotation of said armature controllable by the overall amount ofelectrical energy fed into said electromagnet.

3. A variable time delay device comprising an electromagnetic structurehaving two extended polepieces, with a coil in between said pelepieces,with an opening extending through each said polepiece, with amagnetically attractive shaft completing the magnetic circuit andmovable in openings, with means by which anexternal propelling force canbe coupled to said shaft, with means to connect a periodically varyingelectrical input into said coil, and with the speed of movement of saidshaft being controllable by the amount of electrical energy fed intosaid coil.

4. A variable time delay clutching device comprising an electromagneticstructure having an electrical coil around a corset magnetic material,with a bearing positioned in a gap in said core, with a shaft extendingthrough said bearing, with a frictional face attached'to said shaft,with means for connecting said shaft to a means for applying a rotativeforce to said shaft, with said frictional face being magneticallyattracted'to the abutting surface of said core when the said coil isenergized by a periodically varying electrical input current, and withthe rotative speed of said shaft being controllable by the overall powerinput into said coil.

Germany July 21, 1914

